Apparatus for electrical etching



R. lvl. WEEKS,

APPARATUS Fon ELEcTmcAL momma.

APPLICATION FILED APR. 2. i921. 194279876, Patentedsept. 5, 1922Patented Sept. 5, i922.

RAYMOND IVI. WEEKS, OF NARBER'IH, PENNSYLVANIA, .ASSIGNOR TO WEEKSPHOTO- ENGRAVING COMPANY, INC., OF PHILADELPHIA, PENNSYLVANIA, ACORPORA- TION OF PENNSYLVANIA.

APPARATUS FOR ELECTRICAL ETCHING.

Application led April 2, 1921.

To @ZZ 20710772y it may concern.'

Be it known that I, RAYMOND M. IVEEKs, a citizen of the United States,residing at Narberth, county of Montgomery. and State of Pennsylvania,have invented a new and useful Improvement in Apparatus for ElectricalEtching. of which the following is a full. clear. and -exactdescription. reference being had to the accompanying drawings,

which form a part of this specification.v

My invention relates to apparatus for use in electrical etching and moreespecially to novel construction of the cathode and novel means ofsupporting' and forming electrical l5 connection with the anode, orplate to be etched.

In the process of electrical etching, many plates when etched are foundto be spotty, the spotted portions being found to have been onlyslightly etched as compared to the clean portions of the plat-e.

I have found that the spotted condition of the plate is caused by thecollection of bubbles of hydrogen gas at points on the face of the plateduring the etching process, especially when the plate is supported facedownward directly over the cathode, which is the most. effectivearrangement. The bubbles of hydrogen gas tend to insulate the portionsof the plate against which they rest and prevent the etching action ofthe electric current. with the result that when the etching of the plateis completed the portions protected by the bubbles are imperfectlyetched and the plate has a spotty appearance.

The hydrogen gas is liberated at the cathode, and especially at carboncathodes, by electrolysis of the water in the electrolytic solution, andbubbles through the electrolyte. Such bubbles as come in contact withthe plate adhere to it and tend to insulate the portions to which theyadhere.

The primary objects of my invention are to provide a cathode of such acharacter that the liberation of hydrogen gas will be reduced to aminimum, and to provide means, for suspending the plate to be etched, ofsuch a character that it will be substantially indestructible by theelectrolytic solution and at the same time adapted to effect thesuspension of the plate in the most advantageous position for uniformetching.

Serial No. 457,935.

A 'further object of my invention is to provide a cathode of such acharacter that 1t may be combined with carbon, which effects a rapidaction, and when so combined will prevent the hydrogen liberated a thecarbon from acting to insulate the p ate.

I will now describe my invent-ion in detail with reference to theaccompanying drawings, in which I have shown a preferred embodimentcthereof, and in which` Fig. l is a side elevation, partly cutaway, ofan electrical etching apparatus embodying my invention.

ig. 2 is a cross-sectional view of the subject of Figure l.

Fig. 3 is a plan view of a detail of the cathode construction.

Fig. et is a cross-sectional view. away, of the complete cathode.

Fig. -5 is a perspective view of the plate suspending device.

c is a tank of any suitable construction for containing liquidelectrolyte to the opposite sides of which are secured supports b towhich are secured bus bars c, c provided with longitudinally extendingslots al, al. The bus bars c are suitably connected to the positive poleof a source of electric current. Extending about the tank adjacent itsupper edge is a bus bar e, which is suitably connected to the negativepole of the source of current.

A rod f extends `between the bus bars c, c, its ends extending throughslots (Z, and is adjustably secured thereto by means of nuts threaded onits ends. Hangers g provided with vertical slots i1, are suspended fromrod f and secured together by a slotted bar i which is adjustablysecured to the hangers by means of bolts and wing nuts j. Forked pla-tesupporters lo, formed out of silver and having aligning plate receivingnotches Z in the edges of the arms, are adjustably secured by means ofbolts and wing nuts mto the hangers g. The rod f, hangers g, and bar c'are made of any suitable conducting material, as copper, and lead thecurrent from the bus bars c, c to the plate supporters lc from which itpasses to the plate c, which in the etching process becomes the anode.

Resting on the bottom of the tank a is a partly cut rabbeted frame nwhich may be of Wood and in which is supported carbon plates 0 which areelectrically connected by means of loops of silver Wlre p. Extendingover i the frame and spaced above the carbon plate, as shown in Figure4, is a silver plate g, the edges of Which areI turned over the edges ofthe frame. The silver plate g is electrically connected to the carbonplates o by means of loops of silver Wire lr', to which are connectedsilver lead Wires s Which are connected to the bus bar e. The silverplate and carbon plates, all in electrical connection, serve as acathode in the etching rocess.

lfit be desired, for the purpose of speeding up the etching process,carbon plates t may be suspended Within the tank along its side. Suchplates are connected by means of silver leads u to the bus bar e.

ln operation, the plate fa, to be etched, is supported, horizontallyface downward, in the tank, which has been previously charged Withelectrolyte, by the engagement of opposite edges in the slots Z in thearms of the forked plate supporters 7c, as shown in Figs.

1, 2 Iand 5. AThe current when turned on vpasses from the plate throughthe electrolyte to the cathode and in its passage eects the etching ofthe plate. Practically no hydrogen is liberated on the silver plate qand the 'hydrogen liberated on the carbon plates o f orms into bubbleswhich rise in the space above the carbon plates and adhere to theunderside vof thelsilver plate,.

which prevents them from rising and adhering to the plate being etched.The hydrogen bubbles may be dissipated orescape at the sides of thesilver plate, but in the latter case they will rise to the surface ofthe electrolyte at Vthe edges of the tank clear of the plate o.

l have found that the silver lates alone will serve as an effectivecatho e and their use results in minimizing the liberation of hydrogen.rPhe carbon plates o are nonessential, but serve to accelerate theetching process, and when they are used the silver plate performs thefunction of serving to shield the plate being etched from'the'hydrogenbubbles. rlhe carbon plates t, it will be understood, are alsonon-essential, their function bein to further speed up the etching;their uti ity being greatest in the etching of large plates.

l have also found that by the use of silver in the construction of thecathode plate, supporters and leads immersed in the electrolyte, that.they are practically `indestructible as no etching action takes placeon them and they are una'ected by the electrolyte.

Having now fully described my invention, What l claim and desire toprotect by Letters 'Patent is:

l. Apparatus for electrical etching com- Margate prising an electrolyticbath, means for the support therein of a plate to be etched, said platebeing in electrical connection with the positive Y pole of a source ofcurrent and forming an anode, and a. cathode composed of a materialresistant to action by the electrolyte and which will minimize theformation of hydrogen gas.

2. Apparatus for electrical etching comprisino` an electrolytic. bath,means to support therein a plate to be etched, said plate being inelectrical connection with the positive pole of a source of current andforming an a-node, and a silver plate in electrical connection with thenegative -pole of the source of current and forming a cathode.

3. Apparatus for electrical etching comprising an electrolytic bath,means for the support therein of a plate to be etched, said plate beingin electrical connection with the positive pole of a 'source of currentand forming an anode, and a cathode comprising a carbon plate and asilver platespaced from and overlying said carbon plate, said platesbeing electrically connected to each other and to the negative pole ofthe source of current.

4. Apparatus forv electrical etching comprising an electrolytic bath,means for the support therein of a plate to be etched, said plate beingin electrical connection With the acarbon plate and means forming ashieldl spaced from and overlying said carbon plate,

said carbon plate being in electrical connection With a source ofcurrent.`

6. Apparatus for electrical etching comprising an electrolytic bath,means for the support therein of a plate to be etched, said plate beingin electrical connection with the positive pole of a source of currentand forming an anode, and a cathode comprising a conductor in electricalconnection with a source of electric current and means overlying saidconductor adapted to trap gas formed thereat. i

7. Apparatus for electrical etching comprising an electrolytic-bath,means for the support of a plate 'horizontally face downward therein,said plate being in electrical connection with a source of current andforming an anode, a cathode horizontally disposedin said bath beneathsaid plate, and

said plate adapted to shield the face of said plate from gas formed atsaid cathode.

8. Apparatus for electrical etching comprising an electrolyticbath,pmeans to support a plateto be etched horizontally therein, acathode horizontally disposed beneath said plate, and a supplementarycathode suspended vertically adjacent the sides of said bath.

9.'Apparatus for electrical etching comprising an electrolytic bath,means tov sup- .ed to shield said port a plate to be etched horizontallytherein, a cathode horizontally disposed beneath said plate, asupplementary cathode suspended vertically adjacent the sides of saidbath, and means interposed between said first mentioned cathode and saidplate adaptplate from gas'formed at said cathode.

l0. Apparatus for electrical etching comprising an electrolytic bath, acathode submerged in said bath, and means for supportinga plate thereincomprising a suspension device and a 'l bifurcated electrode adapted toengage the edge of a plate.

11. Apparatus for electrical etching comprising an electrolytic bath, acathode submerged in said bath, and means for supporting a plate thereincomprising a suspension device and a bifurcated electrode the arms ofwhich are provided with aligning notches adapted for the reception ofthe-edge of a plate.

prising an electrolytic bath, a cathode submerged in said bath, andmeans for supporting a plate therein comprising'a" suspension device andan electrode provided with aligning notches for the reception of theedge of aplate, said electrode being etch-resistant and resistant to theaction of the electrolyte.

13. Apparatus for electrical etching comprising an electrolytic bath, acathode submerged in said bath, means for supporting a plate therein anda silver electrode incontact With the plate. Y

14l Apparatus for electrical etching com- 12. Apparatus for electricaletching com! prising an electrolytic bath, a cathode submerged in saidbath, and means for supporting a plate therein comprising a suspensiondevice and a bi'furcated electrode the arms of which diverge and areprovided With plate receiving notches adjacent their.

free ends. p

15. Apparatus lfor electrical etching comprising an electrolytic bath, acathode 'submerged in said bath, and means for supporting a platetherein comprising a suspension device of conductive material and a pairof bifurcated electrodes, adjustable vertically and horizontally, thearms of said electrodes being provided with aligning-platereceivingnotches for the reception of opposite edges of a plate. t

16. Apparatus for electrical etching comprising an electrolytic bath,means for supporting a late to be etched in said bath, a cathode sumergedin said bath, and means affording electrical connection with saidplate and said cathode, said means being etch-resistant and resistant toaction by the electrolyte.

17. Apparatus for electrical etching com'- prising an electrolytic bath,means for the support therein of aplate to be etched, said plate beingin electrical connection With the positive pole of va source of `currentand forming an anode, and a cathode in electrical connection With thenegative pole of a source of current, submer ed in said bath, said plateand said catho e being so positioned that their opposing faces Will liein planes substantially parallel one to the other.

18. Apparatus for electrical etching comprising an electrolytic bath,means for supporting a plate to be etched in 'said bath, a cathodesubmerged in said bath, and means affording electrical connection withsaid plate, said means being etch-resistant and resistant to action bythe electrolyte. .n

.In testimony of Which invention, I have hereunto set my hand, atPhiladelphia, Pa., on this first day of April, 1921.

RAYMOND M. WEEKS.

